The manufacturing of a structural assembly may involve bonding together two or more composite parts along a bondline. For primary structures, part of the manufacturing process may include verifying the quality of the bond between the composite parts prior to placing the structural assembly into service. The process of verifying bond quality may include determining whether the bond is a mechanically robust bond capable of carrying design loads, or a non-structural kissing bond wherein the composite parts are in intimate contact with one another, but are incompletely bonded to one another such that the bond may be unsuitable for carrying design loads.
Non-destructive inspection is a technique that allows for inspection of a structure prior to placing the structure into service. Unfortunately, conventional non-destructive inspection techniques are incapable of discriminating between a mechanically robust bond and a non-structural kissing bond. If the bond quality in a structural assembly cannot be verified by non-destructive inspection, it may be necessary to install secondary mechanical fasteners in the bondline to ensure that the bondline is capable of carrying design loads. Unfortunately, the installation of mechanical fasteners in the bondline adds to the cost, weight, and manufacturing time of the structural assembly.
Destructive testing may provide a means for discriminating between a mechanically robust bond and a non-structural kissing bond. However, destructive testing cannot be used on structures that are intended to be placed into service. In some cases, a test version of a structure may be manufactured in parallel with the in-service version, and the test version may be tested to failure as a means to confirm that the bond in the in-service version is mechanically robust. Quality control may also be maintained through statistical analysis to confirm that the bond in a structure is mechanically robust. Unfortunately, the use of statistical analysis or parallel manufacturing and destructive testing of a test version of a structure adds to the cost, complexity, and schedule of a production program.
As can be seen, there exists a need in the art for a method for non-destructively proving the quality of a bond between composite parts.